Rong-Tao Yang

Effects of intermittent versus continuous parathyroid hormone administration on condylar chondrocyte proliferation and differentiation.

Endochondral ossification is a complex process involving chondrogenesis and osteogenesis regulated by many hormones and growth factors. Parathyroid hormone (PTH), one of the key hormones regulating bone metabolism, promotes osteoblast differentiation and osteogenesis by intermittent administration, whereas continuous PTH administration inhibits bone formation. However, the effects of PTH on chondrocyte proliferation and differentiation are still unclear. In this study, intermittent PTH administration presented enhanced effects on condylar chondrocyte differentiation and bone formation, as demonstrated by increased mineral nodule formation and alkaline phosphatase (ALP) activity, up-regulated runt-related transcription factor 2 (RUNX2), ALP, collagen type X (COL10a1), collagen type I (COL1a1), osteocalcin (OCN), bone sialoprotein (BSP), bone morphogenetic protein 2 (BMP2) and osterix (OSX) mRNA and/or protein expression. On the contrary, continuous PTH administration promoted condylar chondrocyte proliferation and suppressed its differentiation, as demonstrated by up-regulated collagen type II (COL2a1) mRNA expression, reduced mineral nodule formation and down-regulated expression of the mRNAs and/or proteins mentioned above. Our data suggest that PTH can regulate condylar chondrocyte proliferation and differentiation, depending on the type of PTH administration. These results provide new insight into the effects of PTH on condylar chondrocytes and new evidence for using local PTH administration to cure mandibular asymmetry.

Dental trauma in patients with maxillofacial fractures

PURPOSE The purpose of this study was to analyze and evaluate the correlation between dental injuries and the pattern of maxillofacial fractures. The correlation with age, gender, trauma mechanism and type of maxillofacial fracture was also investigated. MATERIALS AND METHODS From January 2000 to December 2009, 1131 patients with facial fractures were registered. Of these, 473 presented with associated dental trauma. The information and data collected and analyzed included: age, gender, mechanism of injury, type of facial fracture, type of dental injury, and the relationship between dental injury and facial fracture. RESULTS Dental injury was sustained by 473 patients (41.8%), with a total of 2215 injured teeth. Of the 2215 injured teeth, 1191 (53.8%) were in the maxilla and 1024 (46.2%) in the mandible. Fall from a height had the highest risk of dental injuries (OR = 4.145, P = 0.002). The central incisor was the most injured tooth for both the maxilla (388, 36.2%) and mandible (284, 27.7%). The most common type of dental injury was avulsion (1070, 47.4%). More anterior teeth in the maxilla were of crown fracture, avulsion, and intrusion than that in the mandible, whereas more anterior teeth in the mandible were of subluxation and concussion than that in the maxilla. Dental injuries were more prone to occur in patients who sustained only symphysis fractures (OR = 2.817, P < 0.001), only 0.236-fold risk in patients who sustained only mandible angle fracture (P < 0.001). CONCLUSIONS The occurrence of dental trauma is significantly related to the pattern and position of the maxillofacial fractures.

Incidence and pattern of maxillofacial fractures in children and adolescents: A 10 years retrospective cohort study

OBJECTIVE The purpose of this study was to evaluate and compare the demographic characteristics of maxillofacial fractures between children and adolescents. METHODS The sample was composed of all children (less than 12 years) and adolescents (between 13 and 18 years old) who presented with maxillofacial fractures during a 10-year period (2000-2009). The age, gender, time of injury, mechanism of trauma, location and pattern of fracture, associated injuries, and treatment methods were recorded and analyzed. Data analysis included Chi-Square test, Fisher exact test. p less than 0.05 was considered significant. RESULTS Seventy-nine children (male-to-female ratio, 1.63:1) and 113 adolescents (male-to-female ratio, 3.52:1) sustained 389 maxillofacial fractures. Children were more involved in falls compared to adolescents (44.3% versus 23.9%, p=0.003), while adolescents sustained more assault-related injuries (13.3% versus 2.5%, p=0.010) and motorcycle accidents (22.1% versus 8.9%, p=0.015) compared to children. Children suffered mandibular fractures proportionally higher than adolescents (93.1% versus 64.5%, p<0.001). Adolescents sustained mid-facial fractures more frequently than children (35.5% versus 6.9%, p<0.001). Severe facial fractures occurred more in adolescents compared to children (35.4% versus 14.1%, p=0.001). Open reduction was done more in adolescents than in children (92.3% versus 74.6%, p<0.001). CONCLUSIONS The incidence and pattern of maxillofacial fractures in children were remarkably different from that in adolescents. Preventive measures and treatment plan should be designed with differences between the two groups in mind.

Changing pattern in the characteristics of maxillofacial fractures.

PurposeThis study was designed to assess the changes in the etiology, incidence, and pattern of maxillofacial fractures during 2 different study periods in our department. Patients and MethodsIn this retrospective study, patients treated for maxillofacial fractures at our department from January 2000 to December 2009 were included. Data regarding patient’s age, sex, etiology of fracture, time of injury, site of fracture, and pattern of fracture were collected and grouped chronologically into two 5-year periods: 2000 to 2004 (period 1) and 2005 to 2009 (period 2); the results of the study during these periods were analyzed and compared. ResultsA total of 1131 patients sustained maxillofacial fractures: 422 in the first period and 709 in the second period. During the second period, the male–female ratio increased from 3.35:1 to 3.63:1. Road traffic accidents remained the major etiologic factor, which increased remarkably from 49.3% to 54.6% (P = 0.085), whereas assault-related injuries decreased significantly from 16.8% to 12.4% (P = 0.039). The proportion of patients with mandibular fractures decreased from 59.6% to 55.3% (P = 0.037), whereas the proportion of patients with midfacial fractures increased from 40.4% to 44.7% (P = 0.037). ConclusionsThe changing pattern of maxillofacial fractures in our center is correlated to the socioeconomic status, population mobility, and etiologic factors. Strict enforcement of traffic laws and regulations is still a focal factor in attaining appreciable reduction in maxillofacial fractures associated with road traffic accidents.

Autophagy Prior to Chondrocyte Cell Death During the Degeneration of Meckel's Cartilage

The central portion of Meckels cartilage degenerates almost immediately after birth. Whether autophagy is involved in this process remains unclear. Thus, to explore the role of autophagy during this process, we have detected the expression of autophagy and apoptosis‐related markers in embryonic mice. In E15, Beclin1 and LC3 expressions were weak and negative in Meckels cartilage, respectively. In E16, chondrocytes of the central portion became hypertrophic. Moderate immunoreactivities of Beclin1 and LC3 were observed in prehypertrophic and hypertrophic chondrocytes of the central portion. In E17, the degradation occurred in the central portion and expanded anteriorly and posteriorly. Beclin1 expression was observed in Meckels cartilage with an increase in the hypertrophic chondrocytes of the central portion. The expression of LC3 was detected specifically in terminally differentiated hypertrophic chondrocytes. The mRNA expressions of LC3 and Beclin1 from E15 to E17 significantly increased. This result is in accord with the histologic findings. Terminal deoxynucleotidyltransferase‐mediated dUTP‐biotin nick‐end labeling assay and Caspase 3 expression demonstrated that apoptosis was detected in the lateral part of terminal hypertrophic chondrocytes along the degeneration area of Meckels cartilage. In addition, Bcl2 expression increased significantly from E15 to E17. These results indicate that autophagy is involved in hypertrophic chondrocytes during the degradation of Meckels cartilage and occurs prior to chondrocyte cell death during this process. Anat Rec, 2012.

Mechanics in the Production of Mandibular Fractures: A Clinical, Retrospective Case-Control Study

As the mandible is susceptible to fracture, the aim of this study was to use multivariate logistic regression analysis to identify and distinguish various internal factors that may influence the location of mandibular fractures. The study included 1131 patients with maxillofacial fractures during the period from January 2000 to December 2009 to evaluate the association of mandibular fracture location (unilateral symphysis, body, angle, condylar, or bilateral condylar fractures) with various internal factors. Among the 1131 patients, 869 had mandibular fractures. Data on age, sex, soft tissue injuries, dental trauma, and maxillofacial fracture type were collected and analyzed using multivariate logistic regression. In total, 387, 210, 139, 319, and 172 patients were diagnosed with unilateral symphysis, body, angle, unilateral, or bilateral condylar fractures, respectively. The dental trauma in patients with bilateral condylar fractures differed from that in patients with unilateral condylar fractures. Patients with mandibular fracture (unilateral symphysis, body, unilateral or bilateral condylar) possessed an approximately equal risk of soft tissue injuries in the mandible. Patients with either unilateral or bilateral condylar fractures were associated with a low risk of mandibular angle fracture (OR < 1). Similarly, patients with mandibular angle fracture were associated with a low risk of unilateral or bilateral condylar fractures (OR < 1). Moreover, patients with symphysis fracture were associated with a low risk of bilateral condylar fractures (90 of 387 [23.3%], OR 0.899). By contrast, patients with bilateral condylar fractures were associated with a high risk of symphysis fracture (90 of 172 [52.3%], OR 17.38). Patients with condylar fractures, particularly those with bilateral condylar fractures, were infrequently associated with secondary mandibular fractures. Mandibular fractures tended to have less of an association with midfacial fractures. The occurrence of mandibular fractures is strongly correlated with age, sex, soft tissue injuries, dental trauma, and the pattern and position of the maxillofacial fractures in patients.

Maxillofacial injuries in infants and preschools: a 2.5-year study.

PurposeThis study aims to evaluate the epidemiology of maxillofacial injuries in infants and preschools. Patients and MethodsThe data from 110 infants and preschools with maxillofacial injuries from October 2010 to March 2013 were analyzed retrospectively. ResultsThe male-to-female ratio was 1.89:1. The peak age was 1 to 3 years (53.64%). Accident falls (76.36%) were the major cause. A total of 166 soft-tissue injuries were found in 103 patients, 102 dental traumas in 36 patients, and 53 maxillofacial fractures in 33 patients. The most common sites of soft-tissue injuries included the gingiva (17.47%), lower lip (13.86%), upper lip (13.25%), and chin (12.05%), and the majority were lacerations (77.71%). Dental traumas occurred mainly in incisors (81.37%) and the lower arch (60.78%). Of the 53 fractures, the most common sites were the condyle (45.28%), symphysis (22.64%), and mandibular body (16.98%); 28 (52.83%) were treated by operation and 25 (47.17%) by conservative treatment. ConclusionsMaxillofacial injuries in infants and preschools exhibit specific epidemiological features. These are related to anatomic, physiologic, and psychologic development in infants and preschools.

Ocular trauma in patients with maxillofacial fractures

PurposeThe purpose of this study was to analyze and evaluate ocular injuries in patients with maxillofacial fractures. Correlation of the ocular injury and patients’ age, sex, trauma mechanism, and type of maxillofacial fracture was also investigated. Materials and MethodsFrom January 2000 to December 2009, a total of 1131 patients with facial fractures were registered. The information and data collected and analyzed included the following: age, sex, mechanism of injury, type of facial fracture, type of ocular injury, and the relationship between ocular injury and facial fracture. ResultsOcular injury (349 injuries) was sustained by 209 patients (18.5%), with a male/female ratio of 5.33:1 (176 males and 33 females). The age range of the patients associated with ocular trauma was 3 to 68 years (mean [SD], 32.40 [11.27] y). Patients aged 30 to 39 years showed the highest risk for ocular trauma (odds ratio [OR], 1.852; P < 0.001). Children showed the lowest risk for ocular injuries (OR, 0.162; P < 0.001). Motor vehicle accidents were the most common mechanism of injury (97 patients, 46.4%). Motor vehicle accidents also had a 2.243-fold risk for ocular trauma (OR, 2.243; P = 0.021). Ocular traumas were more prone to occur in patients who sustained midfacial fractures (OR, 10.232; P < 0.001), especially the patients with multiple midfacial fractures (OR, 12.389; P < 0.001). Fracture of the mandible had the lowest risk for ocular injuries (multimandibular fractures: OR, 0.035, P < 0.001; single mandibular fracture: OR, 0.151; P < 0.001). ConclusionsThe occurrence of ocular injuries was significantly related to sex, age, etiology, as well as the pattern and position of the maxillofacial fractures.

Does traumatic brain injury result in accelerated mandibular fracture healing

PURPOSE To investigate the occurrence of accelerated bone healing evidenced by early callus formation in patients with mandibular fractures and traumatic brain injury (TBI). MATERIALS AND METHODS A retrospective cohort study was performed in patients who presented for mandibular fracture evaluation and management over a 6-year period. Subjects eligible for the study included those who underwent a computed tomographic examination of the mandible more than 2 weeks after the injury and had not undergone surgery with rigid internal fixation. TBI was used as the predictor variable. Time to callus formation as detected on computed tomographic scans was recorded as the primary outcome variable. Other variables considered included age, gender, coma duration, and fracture distribution. Appropriate statistical analyses were performed to determine the influencing factors. RESULTS Forty-five patients with mandibular fractures (24 with severe TBI and 21 without TBI) were retrospectively analyzed. Twelve patients with TBI and 6 without TBI exhibited a visible callus on their computed tomographic scans. Statistical analysis showed no significant differences in age, gender, examination time, and fracture distribution between the groups. Cox proportional hazards regression analysis indicated a positive correlation of time to callus formation with TBI and coma duration but not with age, gender, and fracture distribution. CONCLUSIONS These findings suggest that patients with severe TBI and mandibular fractures exhibit increased fracture healing as evidenced by early callus formation. A more exhaustive study is required to advance the understanding of this phenomenon and provide additional clinical significance.

Risk factor analysis and idiographic features of mandibular coronoid fractures: A retrospective case–control study

This study aimed to identify and distinguish various factors that may influence the occurrence of mandibular coronoid fractures. From January 2000 to December 2009, a total of 1131 patients with maxillofacial fractures were enrolled in this statistical study to evaluate the association between mandibular coronoid fractures and other risk factors. Among these patients, 869 had mandibular fractures, and 25 sustained a total of 25 coronoid fractures. More than half (13 of 25 patients, 52%) of the coronoid fractures in these patients were caused by motor vehicle accidents. Among these coronoid fractures, seven were associated with other mandibular fractures, and 23 (92.0%) were related to midfacial fractures. The most common site of midfacial fracture was the zygomatic arch (20 patients, 80%). Multivariate logistic regression analysis revealed that the most important influencing factor was the zygomatic arch fracture (odds ratio, 9.033; 95% confidence interval, 1.658, 49.218; p = 0.011). The majority of coronoid fracture fragments (19 of 25, 76%) were removed during operation. The most commonly used incision is hemicoronal or bicoronal approach (16 of 19, 84.2%).